We’ve all heard of the “4 C’s” of diamond buying: clarity, color, cut and carat weight. But what do these terms really mean, and how can the average customer apply these factors in making an informed buying decision?
Color. In reality, truly colorless diamonds are quite rare. Most diamonds used in jewelry are nearly colorless with faint yellow or brown tints. These diamonds fall into what is called the normal color range. Diamonds in this normal color range are graded by their relative lack of color on a scale known as the GIA Color Grading System, from D (colorless) to Z (fancy yellow). A diamond that is said to have “fine color” has little or no visible coloration – the less color, the higher the value. It’s nearly impossible for people with no gemological training to see the almost indistinguishable differences in the top five or six color grades, but these differences can cause dramatic variations in price.
Diamonds outside the normal color range are called fancy-colored and come in about any color you can imagine. These include any naturally colored diamond with a noticeable depth of color. Red and green are the rarest fancy colors, followed by purple, violet, orange, blue, pink, and yellow. White, black, and gray are not, strictly speaking, spectral colors, but they are also considered fancies.
Clarity. Diamonds have internal features, called inclusions, and surface irregularities, called blemishes which, together, are called clarity characteristics. Clarity is the relative absence of clarity characteristics. Scratches and nicks on a diamond’s surface are blemishes; inclusions are on the inside and can be tiny diamond or other mineral crystals trapped inside a diamond when it forms, and which are still there after the stone has been cut and polished. Sometimes, a diamond can be recut or polished to remove a surface blemish without noticeably reducing the stone’s weight, which usually increases the diamond’s value. Inclusions, however, cannot be corrected.
The GIA clarity grading scale has various classifications ranging from Fl (flawless), in which the diamond shows no inclusions or blemishes of any sort under 10X magnification, to I1, I2, and I3 , having obvious inclusions that may affect brilliance. As you might expect, truly flawless diamonds are very rare. All other factors being equal, the higher on the clarity chart, the more expensive the diamond.
Cut. This is probably the most complex of the 4 C’s to understand. The untrained eye usually thinks of cut as the shape and style of a polished diamond. But it’s much more than that - there are also proportion, symmetry and finish to consider. Collectively, these factors are often called "make" in the diamond trade. A diamond with a "good make" will be bright, fiery, symmetrical, and will sparkle with light. What makes a cut so difficult to evaluate is that there's more than one way of cutting a diamond to make the most of this interaction with light. A well-cut diamond can make light behave in breathtaking ways.
The three major parts of a polished diamond, top to bottom, are the crown, the girdle, and the pavilion. A pavilion depth that’s too shallow or too deep will allow light to escape from the side of the stone, or leak out of the bottom. A well-cut diamond will direct more light through the crown.
Carat Weight. The last of the 4 C’s – carat weight – has to do with the basic measuring unit of diamonds. A carat is the standard unit of weight used for gemstones. One carat equals .200 grams (or 200 milligrams), and is usually abbreviated ct. Diamonds are weighed to a thousandth (0.001) of a carat and then rounded to the nearest hundredth, or point. For example, a diamond weighing 0.83 ct is said to weigh “83 points” or “an 83-pointer”. Over a carat, diamond weights are usually expressed in carats and decimals (1.03 for example). Large diamonds are rarer than small diamonds. The scarcer a diamond is, the higher its worth. So a larger stone doesn’t just cost more, it also costs more per carat
Remember, as big a factor as each of the 4 C’s may be individually, no one of them is automatically more important than the others. They all have to be factored in together in assessing the true value of a diamond.
A final note: When you have selected your diamond, it will most likely come with what is called a “report”. The GIA Diamond Dossier® Grading Report is the most common of these, and it is simply an objective report on your new purchase. Your diamond has been registered, and your own personal registry number has been laser-inscribed on the stone’s girdle. You can see the registration number under a microscope, and it will match the number on your dossier. Your dossier will include analysis of the 4 C’s we have discussed, and will list the carat weight of your new diamond, the clarity rating, and the color grade. Although there is no grading system for cut, it will list details of the cut of your diamond.
